The specter of racism hangs over the resumption of the Europa League on Thursday, with Liverpool expressing its "major concern'' that the last-32 match against Zenit St. Petersburg will be marred by racist abuse from the Russian team's fans.
Liverpool officials are concerned about the welfare of the club's players in light of a document published by a section of Zenit supporters in December, urging the team not to sign black or gay players.
Liverpool managing director Ian Ayre has written to UEFA and Zenit to detail his concerns, and said players will be briefed about how to respond in the event they suffer abuse.
"The most we can do is make our feelings clear ahead of the game, and hope that we get an adequate response and adequate support on the night,'' Ayre said. "That's about the most we can do at this stage.
"I'm certainly hopeful that the right people will take the right action to ensure it's a game where we don't have that type of incident.''
Zenit coach Luciano Spalletti distanced himself from the document Wednesday, saying the judgment of those particular fans had been "erratic.''
"For me, skin has no color,'' Spalletti said. "The document, published on the internet, expresses the judgment of a separate group of fans but not of all supporters of Zenit and citizens of St. Petersburg.''
Zenit are among a raft of eastern European teams in the last 32 who have yet to resume their domestic league campaigns after the winter break, likely leaving them rusty and struggling for match sharpness.
Sparta Prague faces the same problem ahead of its match against Chelsea, the European champion which dropped into the Europa League after finishing third in its Champions League group.
The London club is expected to take the competition seriously as it is one of only two realistic opportunities for silverware this season.
"It is true the Europa League is not the same as the Champions League because that is the top, but the Europa League is a big competition, an important competition, and now we have the chance to win it,'' Chelsea defender Cesar Azpilicueta said.
"Never in the history of Chelsea have we won this cup and we are going to try to do it.''
Chelsea captain John Terry has traveled to the Czech Republic despite missing the 4-1 league win over Wigan on Saturday with a knee injury, while goalkeeper Petr Cech has a hairline fracture to his little finger on his left hand but should still play against his former club.
"For them, it will be the biggest game of their careers,'' Cech said on Wednesday, "so that's a danger because they will want to show they can do well against us.''
In other high-profile matches, Tottenham hosts Lyon, Ajax is at home to Steaua Bucharest in a match between two former European champions, and Rubin Kazan visits Atletico Madrid, the defending champion bidding to become only the third team to retain the trophy.
Like Chelsea, Liverpool is expected to field a strong team for a first leg set to be played in sub-zero temperatures in Russia, with the Europa League the only remaining trophy available to the five-time European champions.
A disappointing 2-0 home loss to West Bromwich Albion on Monday dropped Liverpool to ninth place in the Premier League, meaning the team is unlikely to qualify for Europe next season unless it wins the Europa League.
"We've got to get the disappointment out of our mind and refocus on our next game,'' Liverpool manager Brendan Rodgers said.
Lyon won more points - 16 - than any other team in the group stage and is preparing to welcome back to the Stade Gerland former goalkeeper Hugo Lloris, who joined Tottenham in August.
"It's not easy for me because I have a good relationship with all my ex-teammates but that is football,'' said the France captain, who has established himself as first-choice goalkeeper at Tottenham but will be on the bench for the first leg. "That is the life. On the pitch there are no friends. We play for our team and give all the best for our team.''
In winger Gareth Bale, Tottenham has arguably the form player in the Premier League and the Wales winger will be looking to score in a fifth straight game in all competitions.
As well as Chelsea and Zenit, the other teams to drop into the Europa League from the Champions League are Dynamo Kiev, Olympiakos, Ajax, Benfica, BATE Borisov and Cluj.